filter/animation/blend behavior?

GIMP version: 2.10.14

Operating System: Windows 10 version 1909 build 18363.592 (Maybe other OS too)

Package: Official Installer

Description of the bug

Blend (Gradation) Color Space Mode is selected Perceptual RGB.

Then, You create a new image with three layers, filling White, Black and White. All layers set Default, Not Legacy. Let's try to make Blend from filter / animation. (ex. 5 frames generation) The result will maybe Linear Gradation! (Tone jump at a bit dark gray to black!)

If you change layer mode to Legacy, you get a correct result.

Is this expected behavior?